Tuft anchoring means for brushes



Oct. 15, 1946. c. Jo BsT TUFT ANCHORING MEANS FOR BRUSHES Filed May 11,1944 INVENTOR. CONRAD JOBST ATTORNEYS Patented Oct. 15, 1946 UNIT-El)STATES; PATENT OFFICE TUFT ANCHORING MEANS FOR BRUSHES Conradlobst,Toledo, Ohio, a ssig nor to The Toe ledo Automatic Brush MachineCompany, To-

ledo, Ohio, a corporation of Ohio Application May 11, 1944, Serial No.535,166

1 Claim.

The invention relates to means for anchoring tufts in brush backs andhas more particular application to brush backs formed of molded plasticmaterial. In the present state of the brush art, molded syntheticplastics have been extensively used for the forming of backs and handlesof brushes. The tufts are set in such backs in much the same way as inthe earlier type of backs formed of other materials. Also it has beenthe practice to secure the tufts by staples or other metallic anchoringmembers.

I have discovered that tufts may be secured within the bores of aplastic brush back by means of an anchor formed of certain types ofplastic materials and that these anchors may be applied by a tuftsetting mechanism such as described in my previous Patent No. 2,084,345of June 22, 1937. The essential features of the mechanism shown anddescribed in this patent are, first, that a strip or ribbon isintermittently advanced to shearing means which severs an anchor lengththerefrom, after which the severed portion is moved laterally into thepath of a driver by which it is driven through the tuft setting nozzleinto a registering bore of the brush back carrying the tuft therewith.While the metallic anchor described in my patent is of slightly greaterlength than the diameter of the bore so that it forms grooves ondiametrically opposite sides of the latter, I have found that theplastic anchor of the present invention need be no larger than the hole.

When the plastic anchor is driven into the hole in the brush back, theplastic material of the anchor softens by means of the heat generatedduring the impact with the brush back and it is deformed into a shapewhich interlocks with the brush back and forms a bond. therewith, thusfirmly holding the bristles in the bore.

The invention will be more fully appreciated by reference to theaccompanying drawing, in which Figure 1 is a cross section through abrush back showing the bristle tuft and plastic anchor as it enters thebore;

Figure 2 is a similar view showing the tuft and anchor after it isinserted in the bore;

Figure 3 is a transverse section on line.3--3 of Figure 2;

Figure 4 is a section on line l-d of Figure 2;

Figure 5 is a side view of an anchor after insertion showing on anexaggerated scale the deformation of the material to conform to thebristles of the tuft;

Figure 6 is a section on the line 6-6 of Figure 5.

I0 is a brush back having a series of tuft-receiving bores ll formedtherein in the usual manner. A tuft of bristles l2 doubled over ananchor I3 is inserted in the bore by means of the driver or inserter Mof a suitable tuft-setting mechanism such as described in my Patent No.2,084,345.

Theanchor is preferably a rectangular slug of a length substantially thesame as the diameter of the bore and of a lesser width. It is severedfrom a strip of relatively thin material in the same manner as set forthin my prior patent.

However, instead of using a corrosion-resistant metal alloy as has beendone in the past, I use a plastic material of a type that will soften oreven melt under the influence of the heat generated by the impact whenthe tuft is inserted in the brush back.

Thus, as shown in Figure 2, the force of the impact causes the ends N5of the anchor to be deformed and to penetrate the side walls of the boreas indicated at I6, thereby forming a mechanical interlock. Moreover,the softening or melting of the ends of the anchor results in theformation of a bond between the anchor and the brush back, which assistsin retaining the anchor in its set position and firmly securing thebristle tuft.

While the anchor is in its softened condition during the insertion, theindividual bristles of the tuft become embedded in the leading edge llof the anchor and to a certain extent in the side faces 18 of theanchor, thereby forming grooves ill in the edge and grooves 20 in theside faces. This is diagrammatically illustrated in Figure 5 where thegrooves are shown on an exaggerated scale.

In the broader phases of my invention, the anchor may be made of anynon-metallic plastic material which is capable of being so influenced bythe impact of the insertion as to form a mechanical interlock or bondwith the brush back to securely hold the tuft in position. Morespecifically, I have found that it is desirable to use a resin which maybe identified as a viny1 chloride-vinyl acetate copolymer containing-95% vinyl chloride and having an average molecular weight of 10,000 to25,000 as determined by the Staudinger method. As an example ofresins'of this type, reference may be made to U. S. Patent No. 1,935,577and to an article by Curme 8; Douglas, published in the October 1936issue of Industrial and Engineering Chemistry.

The material of the brush back may be any of the usual types of plasticscommonly used for this purpose such as Celluloid, cellulose acetate,butyrate, etc.

through the transparent back. A very important advantage is theinterlock which is produced by the lateral expansion of the anchorduring the setting operation. A further advantage is that the materialis not subject to corrosion as is the case with certain metals fromwhich anchors have been formed. An important advantage is that theplastic anchor forms abufier between the driver l4 and the bristle tuft,thus preventing the injury of the bristles during the setting of thetuft in the brush back.

While I have disclosed a preferred embodiment of the invention, it is tobe understood that it is not limited to the specific construction hereindefined, but covers various modifications coming within the purview ofthe appended claim.

What I claim as my invention is:

In combination with a brush back of a polymerized synthetic plasticmaterial and having a bore therein and a bristle tuft within said bore,of an anchor formed of a copolymer of vinyl chloride and vinyl acetate,said anchor having the ends thereof laterally expanded to be embedded inthe walls of said bore and bonded to

